The present invention relates to expansion joint covers for bridging the expansion gaps between building floors and, in particular, to heavy duty expansion joint covers suitable for the floors of structures such as parking decks and parking garages.
In settings such as parking garages and parking decks where vehicles traverse expansion joints, expansion joint covers are subjected to heavy loads, abrasion, water intrusion and other harsh environmental conditions, special attention is needed in designing expansion joint covers that are strong, durable, resistant to deterioration, and capable of being easily serviced and repaired. All parts that the wheels of vehicles travel on should be of metalxe2x80x94elastomeric seals are not sufficiently durable to be long-lasting. The predominant use of metal parts gives rise to noise problems, which are highly objectionable to pedestrians both inside and outside the structure.
An object of the present invention is to provide an expansion joint cover that is xe2x80x9crattle-free,xe2x80x9d provides for relative movements of the floors on opposite sides of the expansion gap toward and away from each other (xe2x80x9cx-axis motionxe2x80x9d), parallel to each other lengthwise of the expansion gap (xe2x80x9cy-axis motionxe2x80x9d), and vertically (xe2x80x9cz-axis motionxe2x80x9d), is relatively inexpensive to produce, is easy to install, allows for on-site adjustment of a xe2x80x9chold-downxe2x80x9d force, and can be readily disassembled for service and repair.
The foregoing objects are attained, according to the present invention, by an expansion joint cover for bridging an expansion gap between first and second building floor members that has a pivot frame adapted to be affixed to the first building floor member, the pivot frame including a base portion and a longitudinally continuous bearing of spherical cross-section supported by and located above the base portion, and a slide frame adapted to be affixed to the second building floor member. A cover unit is pivotally mounted in spaced-apart relation to a proximal end thereof on the bearing in cantilevered relation to the bearing, is adapted to span the gap, and has a distal end supported on the slide frame. A plurality of spaced-apart compression spring units engaged between the base portion of the pivot frame and a portion of the cover unit intermediate the proximal end and the bearing bias the cover unit about the bearing so as to forcibly engage the distal end of the cover unit with the slide frame.
One advantage of an expansion joint cover according to the invention, as described thus far, is that the cover unit is firmly xe2x80x9cpre-tensionedxe2x80x9d with respect to both the pivot frame and the slide frame, which eliminates any looseness that can produce bothersome rattling. A further advantage is that the pre-tensioning is provided by a structure of relatively simple and low-cost construction, a series of compression spring units associated with one frame but acting on both framesxe2x80x94the spring units tighten the cover unit to the bearing on the pivot frame by forces acting upwardly on the proximal end of the cover unit and tighten the cover unit to the slide frame by forces acting downwardly on the distal end of the cover unit.
It is possible for the cover unit to be made in one piece (e.g., an extruded unitary cover and socket) or two pieces (e.g., a cover plate and a separate one-piece pivot block). Such constructions, however, have the disadvantages of requiring a relatively large clearance between the socket and bearing to allow for tolerance variations while permitting assembly by endwise sliding, of not being readily disassembled for repair, presenting difficulties in installing the springs, and limiting the materials of the cover unit and the manufacturing techniques for making the cover unit. Thus, it is preferred that the cover unit be an assembly that includes a cover plate, a first elongated continuous pivot block attached to the cover plate, and a second elongated continuous pivot block attached to the cover plate, each pivot block having a socket portion engaging a circumferential portion of the bearing. The cover plate may be fabricated from plate material, which may be aluminum, stainless steel, galvanized steel or a composite material. The two-part construction of the pivot block allows it to be installed without endwise sliding and permits disassembly and removal from the bearing. Preferably, the socket portions of the two pivot blocks have contiguous surfaces, the cover plate is attached to each of the pivot blocks by threaded fasteners, and the socket portion of each of the pivot blocks receives a spline of a resilient polymeric material to take up tolerance variations. A lubricant is provided at interfaces between the bearing and the socket portions of the pivot blocks.
Assembly is facilitated by interconnecting the pivot blocks by mating hook portions, which are arranged such that the second pivot block can be fitted to the bearing and interconnected to the first pivot block after the first pivot block is fitted to the bearing. The interconnection keeps the two pivot blocks joined to each other while the cover plate is attached to the second pivot block.
In advantageous embodiments, the first pivot block is located generally proximally of the bearing, the socket portion of the first pivot block is substantially semi-cylindrical so as to have a portion underlying the bearing and a portion overlying the bearing, the second pivot block is located distally of the bearing, and the socket portion of the second pivot block has a portion underlying the bearing. The underlying portions of the first and second pivot blocks retain the cover unit on the bearing against upward displacement, and the overlying portion of the first pivot block supports the cover unit on the bearing against downward loads. The first pivot block includes a flange portion located proximally of the socket portion and is fastened to the cover plate by screws that pass from above the cover plate through holes in the cover plate and are threaded into holes in the flange portion. The second pivot block includes a longitudinally continuous upwardly open nut groove receiving spaced apart nuts, and the cover plate is fastened to the second pivot block by bolts that pass from above the cover plate through holes in the cover plate and are threaded into the nuts.
According to another preferred aspect of the present invention, each of the compression spring units is received between the base portion of pivot frame and the flange portion of the first pivot block. Each spring unit includes a spring retainer that is affixed to and dependent from the underside of the flange portion of the first pivot block. The spring retainer of each spring unit is tubular, has internal threads, and receives an externally threaded spring force adjuster against which the upper end of the spring bears, the adjuster being accessible through a hole in the flange portion of the first pivot block and a hole in the cover plate so that the spring force of the spring is adjustable after the cover plate is installed. Adjustable spring units facilitate installation of the expansion joint cover by allowing the springs to be installed in an unloaded condition before the pivot blocks are assembled to the bearing and allow predetermined spring loads to be applied with the expansion joint cover nearly fully installed. Advantageously, the holes providing access to the spring adjuster are the holes in the cover plate and the first pivot block that receive the screws by which the cover plate is fastened to the first pivot block.
The springs of the spring unit may be mechanical coil springs, mechanical leaf springs, mechanical disc springs, elastomeric pads or blocks, and springs that include fluids.